U.S. patent number 7,018,416 [Application Number 10/080,375] was granted by the patent office on 2006-03-28 for bone implants and methods.
This patent grant is currently assigned to Zimmer Spine, Inc.. Invention is credited to David A. Hanson, Ross A. Longhini, Daniel D. McPhillips, Steven J. Seme.
United States Patent |
7,018,416 |
Hanson , et al. |
March 28, 2006 |
**Please see images for:
( Certificate of Correction ) ** |
Bone implants and methods
Abstract
Implants, instruments and methods for bone fusion procedures are
disclosed. In some embodiments, the implants are particularly
advantageous for use between opposing vertebral bodies to
facilitate stabilization or arthrodesis of an intervertebral joint.
The implants include, at least, a support component that provides
structural support during fusion. In a typical embodiment, the
implants also include a growth component. A growth component
provides an environment conducive to new bone growth between the
bones being fused. Several unique configurations to enhance fusion,
instruments for insertion and methods for insertion are also
disclosed.
Inventors: |
Hanson; David A. (St. Louis
Park, MN), Longhini; Ross A. (West Lakeland, MN),
McPhillips; Daniel D. (Ham Lake, MN), Seme; Steven J.
(Savage, MN) |
Assignee: |
Zimmer Spine, Inc.
(Minneapolis, MN)
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Family
ID: |
46280334 |
Appl.
No.: |
10/080,375 |
Filed: |
February 19, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20030028197 A1 |
Feb 6, 2003 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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09896926 |
Jun 28, 2001 |
6635060 |
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09611237 |
Jul 6, 2000 |
6641582 |
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60269777 |
Feb 16, 2001 |
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Current U.S.
Class: |
623/17.16 |
Current CPC
Class: |
A61F
2/4611 (20130101); A61F 2/4465 (20130101); A61B
17/1671 (20130101); A61B 17/1757 (20130101); A61F
2002/30879 (20130101); A61B 17/1735 (20130101); A61F
2002/30599 (20130101); A61F 2002/3082 (20130101); A61B
17/1604 (20130101); A61F 2002/30593 (20130101); A61F
2220/0025 (20130101); A61F 2/4603 (20130101); A61B
2017/0256 (20130101); A61B 17/1659 (20130101); A61F
2/30744 (20130101); A61F 2002/30383 (20130101); A61F
2250/0063 (20130101); A61F 2002/30892 (20130101); A61F
2230/0013 (20130101); A61F 2/442 (20130101); A61F
2002/30131 (20130101); A61F 2002/30904 (20130101) |
Current International
Class: |
A61F
2/44 (20060101) |
Field of
Search: |
;623/17.11,17.12,17.13,17.14,17.15,17.16,23.51,23.6,23.61,23.63,23.76
;606/61,76 |
References Cited
[Referenced By]
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Other References
Branch Jr., M.D , Charles L.; Surgical Technique Manual for the
"Tangent.TM. Posterior Discectomy & Grafting Instrumentation
Set" Medtronic Sofamor Danek, publisher. cited by other .
"Tangent.TM. Posterior Discectomy & Grafting Instrumentation
Set: Surgical Technique," Medtronic Sofamor Danek, 26 pgs. (1999).
cited by other.
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Primary Examiner: Reip; David O.
Attorney, Agent or Firm: Faegre & Benson LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Patent Application
60/269,777, filed on Feb. 16, 2001, and is a continuation-in-part
of U.S. patent application Ser. No. 09/896,926, filed on Jun. 28,
2001, now U.S. Pat. No. 6,635,060. U.S. patent application Ser. No.
09/896,926 is a continuation-in-part of U.S. patent application
Ser. No. 09/611,237 filed Jul. 6, 2000, now U.S. Pat. No.
6,641,582.
Claims
We claim:
1. A bone implant comprising: a support member sized for
intervertebral implantation, the support member defining a cavity
having an open end positioned opposite from a closed end; and a
growth member sized to be inserted into the cavity of the support
member through the open end of the cavity after implantation of the
support member into an intervertebral space, the growth member
having a pre-manufactured shape that generally complements a shape
of the cavity, wherein the growth member includes oppositely
positioned bone engagement surfaces separated by a thickness, and
wherein the growth member also includes planar side wall surfaces
that extend between the bone engagement surfaces.
2. The bone implant of claim 1 wherein the open end of the cavity
and the growth member are relatively sized such that the growth
member can be inserted into the cavity through the open end without
requiring expansion of the support member.
3. The bone implant of claim 1, wherein the support member includes
cortical bone and the growth member includes cancellous bone.
4. The bone implant of claim 1, wherein the growth member comprises
an osteoconductive insert block.
5. The bone implant of claim 4, wherein the open end of the cavity
has a width along a direction, and the cavity has an internal
dimension along the direction, the internal dimension being greater
than the width of the open end.
6. The bone implant of claim 5, wherein the bone engagement
surfaces are planar.
7. The bone implant of claim 6, wherein the side wall surfaces are
generally perpendicular relative to the bone engagement
surfaces.
8. The bone implant of claim 5, wherein the insert block includes a
first end positioned opposite from a second end, the first end
including a nose having a curvature that generally matches a
curvature of the curved inner wall of the cavity.
9. The bone implant of claim 8, wherein the insert block includes
substantially parallel sidewall surfaces that extend between the
first and second ends.
10. The bone implant of claim 9, wherein the second end of the
insert block includes a substantially planar surface that extends
between the sidewall surfaces.
11. The bone implant of claim 10, wherein the substantially planar
surface is generally perpendicular relative to the sidewall
surfaces.
12. The bone implant of claim 8, wherein the insert block includes
substantially parallel bone engagement surfaces that extend between
the first and second ends.
13. The bone implant of claim 5, wherein the growth member is
non-threaded.
14. The bone implant of claim 4, wherein the insert block includes
oppositely positioned planar bone engagement surfaces.
15. The bone implant of claim 4, wherein the cavity of the support
member is defined by opposing inner wall surfaces that extend from
the open end of the cavity toward to closed end of the cavity, and
wherein the closed end of the cavity is defined by a curved inner
wall surface that extends between the opposing inner wall
surfaces.
16. The bone implant of claim 1, wherein the growth member is
non-threaded.
17. A bone implant comprising: a support member size for
intervertebral implantation, the support member defining a cavity
having an open end positioned opposite from a closed end; and a
growth member sized to be inserted into the cavity of the support
member through the open end of the cavity after implantation of the
support member into an intervertebral space, the growth member
having a pre-manufactured shape that generally complements a shape
of the cavity, wherein the support member includes oppositely
positioned load bearing surfaces separated by a thickness, wherein
the growth member includes oppositely positioned bone engagement
surfaces separated by a thickness, and wherein the thickness of the
growth member is greater than the thickness of the support
member.
18. The bone implant of claim 17, wherein the thickness of the
support member varies such that the support member has a wedge
shape.
19. The bone implant of claim 18, wherein the thickness of the
growth member is substantially constant.
20. The bone implant of claim 19, wherein the thickness of the
support member is larger adjacent the open end of the cavity than
adjacent the closed end of the cavity.
21. The bone implant of claim 17, wherein the growth member is
non-threaded.
22. An implant comprising a partial cortical ring defining an inner
pocket, the partial cortical ring having a thickness defined
between first and second load bearing surfaces, the inner pocket
being open adjacent the first and second load bearing surfaces, the
partial cortical ring also defining a radial opening for providing
access to the inner pocket, the radial opening being positioned
opposite from a closed end of the inner pocket; a non-threaded
cancellous insert block having a pre-manufactured shape that
complements the shape of the inner pocket, the insert block being
insertable into inner pocket through the radial opening, the insert
block having a thickness defined between first and second bone
engagement surfaces, the thickness of the insert block being
greater than the thickness of the partial cortical ring.
Description
FIELD OF THE INVENTION
This invention pertains to bone implants, instruments and
procedures. Specifically, the invention provides bone implants,
instruments and methods to facilitate fusion of bone. The invention
is particularly suited for stabilization or fusion of the
intervertebral disc space between adjacent vertebrae.
BACKGROUND OF THE INVENTION
Chronic back problems cause pain and disability for a large segment
of the population. Frequently, the cause of back pain is traceable
to diseased disc material between opposing vertebrae. When the disc
material is diseased, the opposing vertebrae may be inadequately
supported, resulting in persistent pain. Surgical techniques have
been developed to remove all or part of the diseased disc material
and fuse the joint between opposing vertebral bodies. Stabilization
and/or arthrodesis of the intervertebral joint can reduce the pain
associated with movement of a diseased intervertebral joint. Spinal
fusion may be indicated to provide stabilization of the spinal
column for a wide variety of spine disorders including, for
example, structural deformity, traumatic instability, degenerative
instability, post-resection iatrogenic instability, etc.
Generally, fusion techniques involve partial or complete removal of
the diseased disc and packing the void area with a suitable matrix
for facilitating a bony union between the opposing vertebral
bodies.
Surgical devices for facilitating interbody fusion are known. Some
devices are positioned external to the intervertebral joint during
the fusion process. Other devices are positioned within the
intervertebral joint. Devices positioned within the joint space
typically distract the joint space and provide stabilization by
causing tension on the annulus fibrosus and other supporting
tissues surrounding the joint space. Examples of devices positioned
within the joint space are disclosed in, for example, U.S. Pat.
Nos. 5,458,638, 5,489,307, 5,055,104, 5,026,373, 5,015,247,
4,961,740, 4,743,256 and 4,501,269, the entire disclosures of which
are incorporated herein by reference. Some systems use both
external fixation and internal fixation devices.
Regardless of the type or location of the fusion device, a bone
graft and/or other implant is often used to facilitate new bone
growth. The surface area, configuration, orientation, surface
texture and deformity characteristics of an implant or bone graft
placed in the disc space can affect the stability of the joint
during fusion and thus affect the overall success of a fusion
procedure.
Accordingly, the present invention is directed to unique implants
or bone grafts that can be inserted at a fusion site, with or
without other stabilizing systems, and instruments and methods for
inserting the same.
SUMMARY OF THE INVENTION
One inventive aspect of the present disclosure relates to an
implant (e.g., a spinal implant) having a first component having
support mechanical characteristics and a second component having
mechanical characteristics for allowing bone in-growth. Other
inventive aspects include systems and methods for implanting
multi-component implants. It should be noted that the examples are
provided for illustrative purposes and are not intended to limit
the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an implant that is an embodiment of
the present invention;
FIG. 2 is a top plan view of the implant of FIG. 1;
FIG. 3 is a front elevational view of the implant of FIG. 1;
FIG. 4 is a side elevational view of the implant of FIG. 1;
FIG. 5 is a perspective view of a portion of the implant of FIG.
1;
FIG. 6 is a front elevational view of the implant of FIG. 5;
FIG. 7A is a perspective view of an implant cap that is an
embodiment of the present invention;
FIG. 7B is a side elevational view of the cap of FIG. 7A;
FIG. 7C is a top plan view of the cap of FIG. 7A;
FIG. 7D is a front elevational view of the cap of FIG. 7A;
FIG. 8A is a top plan view of an inferior vertebrae prior to a
preparation step according to the principles of the present
invention;
FIG. 8B is a front elevational view of the inferior vertebrae of
FIG. 8A and a corresponding superior vertebrae;
FIG. 9A is a top plan view of the inferior vertebrae of FIG. 8A
after a preparation step according to the principles of the present
invention;
FIG. 9B is a front elevational view of the inferior vertebrae and
the superior vertebrae of FIG. 8B after the preparation step of
FIG. 9A;
FIG. 10A is a top plan view of the inferior vertebrae of FIG. 9A
after another preparation step according to the principles of the
present invention;
FIG. 10B is a front elevational view of the inferior vertebrae and
the superior vertebrae of FIG. 9B after the preparation step of
FIG. 10A;
FIG. 11 is a front elevational view of the inferior vertebrae and
the superior vertebrae of FIG. 10B after placement of a support
member in accordance with the present invention;
FIG. 12 is a front elevation view of the inferior vertebrae and the
superior vertebrae of FIG. 11 after placement of a growth member in
accordance with the present invention;
FIG. 13 is a perspective view of an implant kit that is an
embodiment of the present invention;
FIG. 14 is a perspective view of a wedge and portal assembly of the
implant kit of FIG. 13;
FIG. 15 is a top plan view of a rasp that is an embodiment of the
present invention;
FIG. 16 is a side elevational view of the rasp of FIG. 15;
FIG. 17 is a proximal end-on elevational view of the rasp of FIG.
15;
FIG. 18 is an enlarged partial perspective view of teeth on a rasp
head of FIG. 15;
FIG. 19 is an enlarged partial top plan view of a rasp head of the
rasp of FIG. 15;
FIG. 20 is a top plan view of a bone-cutting instrument that is an
embodiment of the present invention;
FIG. 21 is a side elevational view of the bone-cutting instrument
of FIG. 20;
FIG. 22 is a distal end-on elevational view of the bone-cutting
instrument of FIG. 20;
FIG. 23 is a top plan view of an implant insertion tool that is an
embodiment of the present invention;
FIG. 24 is a side elevational view of the implant insertion tool of
FIG. 23;
FIG. 25 is a distal end-on elevational view of the implant
insertion tool of FIG. 23;
FIG. 26 is a side elevational view of a sleeve that is an
embodiment of the present invention;
FIG. 27 is a cross-sectional view of the sleeve of FIG. 26;
FIG. 28 is an end-on elevational view of the sleeve of FIG. 26;
FIG. 29 is a top plan view of an insertion tool handle that is an
embodiment of the present invention;
FIG. 30 is a cross-sectional view of the handle of FIG. 29 taken
along line 30--30;
FIG. 31 is an end-on elevational view of the handle of FIG. 29;
FIG. 32 is side elevational view of an implant insertion tool that
is another embodiment of the present invention;
FIG. 33 is a top plan view of the implant insertion tool of FIG.
32;
FIG. 34 is a perspective view of a portal insertion step according
to the principles of the present invention;
FIG. 35 shows a vertebrae preparation step using a rasp according
to the principles of the present invention;
FIG. 36 shows a vertebrae preparation step using a box chisel
according to the principles of the present invention;
FIG. 37 is a perspective view of a support member being positioned
upon an insertion tool according to the principles of the present
invention;
FIG. 38 shows a support member insertion step according to the
principles of the present invention;
FIG. 39 is shows a growth member insertion step according to the
principles of the present invention;
FIG. 40 shows a portal extraction step according to the principles
of the present invention;
FIG. 41 is a perspective view of an implant that is another
embodiment of the present invention;
FIG. 42 is a side elevational view of the implant of FIG. 41;
FIG. 43 is a front elevational view of the implant of FIG. 41;
and
FIG. 44 is a top plan view of the implant of FIG. 41.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed toward the fusion of bones. The
invention provides natural and/or synthetic bone implants that can
function as a bone graft between adjacent bones to be fused. The
implants of the invention include unique arrangements,
configurations and components to facilitate fusion and maintain
stability during the fusion process.
The implants, instruments and methods of the invention can be used
in a variety of bone fusion procedures. In some embodiments, the
invention may be particularly advantageous for intervertebral
stabilization or arthrodesis of the intervertebral disc space
between adjacent vertebrae. Accordingly, for purposes of
description herein, the invention will be described by reference to
intervertebral fusion procedures in the lumbar region of the spine.
However, this description is for exemplary purposes only and should
not be construed to limit the intended scope of use of the
disclosed implants, instruments or methods. For example, in the
case of vertebral fusion, the implants, instruments and methods of
the invention can be used to fuse cervical, thoracic, lumbar or
lumbo-sacral vertebrae.
In general, the implants, instruments and methods of the invention
are directed to facilitating greater continuity between the bone
formed at the fusion site and the bones fused. The implants are
also designed to provide greater structural support at the fusion
site to maintain stability and alignment at the fusion site, to
reduce healing time and optimize the structural integrity of the
new bone formed at the fusion site. The implants of the invention
can also facilitate the ease of implanting and positioning implants
at a fusion site.
The implants can be prepared from natural materials, synthetic
materials, or a combination of natural and synthetic materials. As
used herein, "natural material" means "bone" and includes bone
harvested from humans or animals. "Bone" may further include
heterologous, homologous and autologous (i.e., xenograft,
allograft, autograft) bone derived from, for example, fibula,
tibia, radius, ulna, humerus, cranium, calcaneus, tarsus, carpus,
vertebra, patella, ilium, etc. Bone may further include one or more
bone products which have been partially or completely
demineralized, prepared for transplantation (e.g., via removal of
immunogenic proteins), and/or processed by other techniques.
Additionally, the implants can be prepared from products made from
bone, such as chips, putties, and other similar bone products. In
some embodiments, human source bone is preferred for human
applications. In a preferred embodiment, the bone of an implant can
be cancellous and/or cortical.
Cortical implant material can be obtained from known long bones,
such as the humerus, radius, ulna, tibia, femur, fibula, etc.
Cancellous material can be obtained from the patella, distal
condyles, tibial plateau, femoral head, etc. Cranial, pelvic (e.g.
iliac crest) and patellar bone can advantageously provide both
cortical and cancellous bone in a single piece. Indeed, these
sources can provide an implant having cancellous bone surrounded on
opposing sides by cortical bone.
"Synthetic materials" include non-bone materials such as titanium,
stainless steel, porous titanium, ceramic, carbon fiber, silicon,
methylmethacrylate, polytetrafluoroethylene, polycarbonate
urethane, PEEK and other materials suitable for use as an
orthopedic implant. Further, the materials may include any of the
above synthetic materials combined with a natural bone material.
For example, the material may comprise a combination of bioglass
and bone chips or bone chips with a bonding agent. As stated above,
an implant of the invention can consist solely of a synthetic
material. In other applications, a synthetic material may be used
in combination with cancellous bone.
In one embodiment, an implant can include a support component or
member and a growth component or member. The support component
includes a material having mechanical properties suitable for
providing, support, stabilization or alignment at the fusion site.
An exemplary material for the support component includes cortical
bone. The growth component includes a material having mechanical or
physical properties that allow or support new bone in-growth. An
exemplary material for the growth component includes cancellous
bone. In such an embodiment, the support component of the implant
provides strength for column support and/or stabilization, and the
growth component facilitates tissue growth, vascularization and
deposition of new bone (e.g., by providing increased surface area).
In one embodiment, the support component includes a material that
provides greater axial column strength than the growth component,
and the growth component includes a material that allows for
enhanced bone in-growth as compared to the support component.
As indicated above, in some embodiments, the "support" portion
(component) of an implant of the invention is provided by cortical
bone or a natural or synthetic material having biomechanical and
biological characteristics similar to cortical bone. The support
portion provides support, stabilization, and facilitates alignment
at the fusion site. The "growth" portion (component) of the implant
can include a material that allows bone in-growth (i.e., an
osteoconductive material) such as a bone growth matrix. In these
embodiments, the growth portion provides a matrix or scaffold to
support new bone growth. One preferred bone growth component that
can also provide some support is cancellous bone. "Porous"
synthetic materials can also act as a supporting, growth component.
As used herein, a "porous synthetic material" includes, for
example, porous titanium, porous ceramics, porous stainless steel
and like materials. Such porous materials can provide
characteristics of both the growth portion and the support portion
of the implant.
In some embodiments, the growth component of the implant can be
prepared from cancellous bone or alternatively a bone growth matrix
shaped into any one of the advantageous configurations of growth
components disclosed herein. Suitable bone growth matrices can be
resorbable or nonresorbable, and with or without osteoinductive
properties or materials. Examples of suitable osteoconductive
matrices include synthetic materials, such as Healos.TM., available
from Orquest, Mountain View, Calif. Examples of osteoinductive
materials include bone marrow, blood platelets and/or bone
morphogenic proteins (BMPs).
An implant of the invention can have one of several configurations
including a single component or a plurality of components. In one
embodiment, the implants have first and second bearing surfaces,
which in use are positioned adjacent opposing vertebrae endplates.
The bearing surfaces can include an engaging surface having a
surface texture that enhances stability at the bone-implant
interface and reduces the likelihood of motion during the fusion
process. Examples of engaging surfaces suitable for the invention
include ridges, knurls, grooves, teeth, serrations, etc.
Natural or synthetic bone implants of the invention can be
manufactured using procedures known in the art. Methods for
preparing natural bone implants are disclosed in for example, U.S.
Pat. Nos. 6,033,438; 5,968,047; 5,585,116; 5,112,354; and
5,439,684; the entire disclosures of which are incorporated herein
by reference.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
The implants, instruments and methods of the invention will now be
described by reference to the several drawing figures. The
functional features of the implants of the invention can be
embodied in any of a number of specific configurations. It will be
appreciated, however, that the illustrated embodiments are provided
for descriptive purposes and should not be used to limit the
invention. In addition, in many exemplary embodiments, cortical and
cancellous bone are used. It will be appreciated from an
understanding of the present invention that the cortical or support
and/or growth portions of the implants can be substituted with
synthetic materials.
I. Representative Bone Implant
FIGS. 1 4 illustrate a multi-piece bone implant 320 that is a
representative embodiment of the present invention. The bone
implant 320 includes a bone support member 341 (also referred to as
a support component or support portion) configured for
intervertebral implantation. As best shown in FIG. 1, the bone
support member 341 defines a cavity 327 (i.e., a void, pocket or
channel) having an open end 342 positioned opposite from a closed
end 343. The bone implant 320 also includes a growth member 321
(also referred to as a growth component or growth portion) having a
shape that generally corresponds to or matches (i.e., complements)
a shape of the cavity 327. The open ended configuration of the
cavity 327 allows the growth member 321 to be inserted into the
cavity 327 through the open end 342. In one embodiment, the growth
member 321 is inserted after the bone support member 341 has been
implanted between adjacent vertebrae. In another embodiment, the
bone support member 341 is implanted such that the open end 342 of
the bone support member 341 faces in an anterior direction (i.e.,
toward the ventral surface of the patient), and the growth member
321 is inserted into the cavity 327 using an anterior approach.
Alternatively, the open end 342 may face in an anterior-lateral or
lateral direction and the growth member 342 may be inserted using
an anterior-lateral or lateral approach, respectively.
A. Bone Support Member
Referring to FIG. 2, the bone support member 341 of the implant 320
has a generally "C-shaped" configuration and includes outer and
inner wall surfaces 323, 324. The shape of the bone support member
341 can also be described as "partial ring-shaped", "U-shaped",
"semi-annular", or generally "horseshoe-shaped". In a preferred
embodiment, the bone support member 341 includes first and second
arms 325, 326 that are integrally connected at mid-line ML.
Interior portions of the arms 325, 326 oppose one another so as to
define the cavity 327 of the support member 341 therebetween. For
example, the inner wall surface 324 includes opposing portions 325a
and 326a, respectively, defined by the arms 325, 326. The opposing
portions 325a, 326a extend on opposite sides of the mid-line ML
from the open end 342 of the cavity 327 to the closed end 343 of
the cavity 327.
Referring still to FIG. 2, the opposing portions 325a, 326a of the
inner wall surface 324 include opposing curved portions 325b, 326b
located adjacent the closed end 342 of the cavity 327 and opposing
planar portions 325c, 326c located adjacent the open end 342 of the
cavity 327. The curved portions 325b, 326b are shown having a
concave, circular curvature. The planar portions 325c, 326c are
generally parallel and define an insertion channel 371 for guiding
the growth member 321 into the cavity 327 during insertion, and for
aligning the growth member 321 within the cavity 327. In a
preferred embodiment, the insertion channel is sufficiently wide
between the planar portions 325c, 326c to receive the growth member
321 therein without requiring the arms 325, 326 to be flexed apart.
The outer wall surface 323 of the support member 341 is shown
including a convex, circular curvature that is concentric with the
curvature defined by the curved portions 325b, 326b of the inner
wall surface 324. In other embodiments, the support member 341 may
be non-circular and/or not curved at all. For example, the support
member 341 could include other shapes such as rectangles, squares,
ovals, ellipses, etc.
FIGS. 5 and 6 illustrate the support member 341 with the growth
component 321 removed from the cavity 327. As can be seen, inner
wall 324 includes a first groove 336 extending partially along
first arm 325 and a second groove 337 extending partially along
second arm 326. The grooves 336, 337 (e.g., slots) oppose one
another and extend from the open end 342 of the cavity 327 toward
the closed end 343 of the cavity 327. At least portions of the
grooves 336, 337 are preferably defined by the planar portions
325c, 326c of the inner wall surface 324. Although grooves 336 and
337 are shown as being discontinuous, the groove can be continuous
around inner wall 324. As will be described below, grooves 336 and
337 provide for attachment of a cover 350 (FIGS. 7A 7D) or an
implant insertion tool 800 (FIGS. 23 and 24). While the grooves
336, 337 are shown including rectangular cross-sections, other
shaped cross-sections such as rounded or triangular shapes could
also be used. Further, the portions of the tool 800 or the cover
350 may or may not be complementary with the shapes of the
grooves.
Referring to FIG. 4, the bone support member 341 includes first and
second bearing surfaces 328, 329 separated by a height or thickness
of the support member 341. The inner and outer wall surfaces 323,
324 extend generally perpendicularly between the first and second
bearing surfaces 328, 329. In the illustrated embodiment, the first
bearing surface 328 includes an engaging surface comprising ridges
328a, and the second bearing surface 329 includes an engaging
surface comprising ridges 329a. As discussed previously, engaging
surfaces reduce the likelihood of post-implantation mobility of an
implant.
Referring to FIGS. 5 and 6, the cavity 327 of the bone support
member 341 preferably extends completely through the bone support
member 341 between the top load bearing surface 328 and the bottom
load bearing surface 329. Thus, the cavity 327 is open on the top
and bottom sides of the bone support member 341 to facilitate
exposure of top and bottom surfaces of the growth member 321 to the
endplates of adjacent vertebrae when the growth member 321
positioned within the cavity 327.
While the bone support member 341 can have a constant height, in a
preferred embodiment, the support member 12 is slightly tapered so
as to define a wedge shape. In one embodiment, the bone support
member 341 can include a lordotic taper at an angle .theta. in the
range of 0 16 degrees (see FIG. 4). As shown in FIG. 4, in an
exemplary embodiment with a lordotic taper, the support member 341
has a maximum thickness H.sub.max adjacent the open end 342 of the
cavity 327 and a minimum thickness H.sub.min adjacent the closed
end 343 of the cavity 327. In certain embodiments, a gradual taper
is provided between the two thicknesses H.sub.max and
H.sub.min.
In one non-limiting embodiment, the support member 341 can have a
maximum depth D in the range of 20 30 mm, a maximum width W in the
range of 20 30 mm, an average thickness (the average of the two
thicknesses H.sub.max and H.sub.min) in the range of 6 24 mm. In
another embodiment, the support member 341 is made of a homogeneous
material having consistent (i.e., non-varying) mechanical
properties. For example, in one embodiment, the support member 341
can include a bone material having a consistent degree of
mineralization. In other embodiments, the support member 341 can
include regions of decreased mineralization (e.g., demineralized
portions) that provide regions of increased flexibility. In a
preferred embodiment, the support member 341 includes a cortical
bone cross-section from a femur or tibia bone.
B. Bone Growth Member
In certain embodiments, the growth member 321 preferably has a
pre-manufactured or pre-formed shape. The terms "pre-manufactured"
and "pre-formed" mean that the growth member 321 has a pre-defined
shape prior to insertion in the cavity 327. In some embodiments,
the pre-manufactured shape of the growth member 321 complements the
shape of the cavity 327. In certain other embodiments, the growth
member 321 includes multiple sub-units having pre-defined
individual shapes and/or having collective shapes. In another
embodiment, the growth member 321 includes a block of cancellous
bone having a shape that complements the shape of the cavity
327.
As shown in FIG. 2, the bone growth member 321 includes a first end
370 positioned opposite from a second end 372. The first end 370
includes an end curvature that generally matches the curvature of
the inner wall surface 324 adjacent the closed end 343 of the
cavity 327. The bone growth member 321 also includes substantially
parallel sidewall surfaces 374 that extend between the first and
second ends 370 and 372. The second end 372 of the bone growth
member 321 includes a substantially planar surface 376 that extends
between the sidewall surfaces 374. In one preferred embodiment, the
planar surface 376 is generally perpendicular relative to the
sidewall surfaces 374. The bone growth member 321 also may include
top and bottom surfaces 378 and 380 that are generally parallel
relative to one another. In the embodiment shown, the top and
bottom surfaces 378 and 380 extend between the first and second
ends 370 and 372 of the bone growth member 321 and are generally
perpendicular relative to the sidewall surfaces 374 and the planar
end surface 376. In the depicted embodiment, the bone growth member
321 has a thickness H.sub.gm that is substantially constant from
the first end 370 to the second end 372. In alternative
embodiments, the thickness can taper gradually along the entire or
part of the distance between the first and second ends 370 and 372.
In some preferred embodiments, the thickness H.sub.gm of the bone
growth member 321 is greater than the thickness H.sub.max of the
bone support member 341. In these embodiments, the thickness
H.sub.gm is preferably at least 2 or 3 mm greater than the
thickness H.sub.max.
In certain embodiments, the top and bottom surfaces 378 and 380 are
adapted for direct contact with cancellous bone upon implantation.
In these embodiments, to promote bone growth, it is desirable for
the surface area provided by the top and bottom surfaces 378 and
380 to provide a significant portion of the total contact area
provided by the implant 320 (the combined contact area provided by
both the support member 341 and the bone growth member 321). In one
embodiment, the top and bottom surfaces 378 and 380 provide at
least 20 percent of the total contact area. In another embodiment,
the top and bottom surfaces 378 and 380 provide at least 25 percent
of the total contact area. In still another embodiment, the top and
bottom surfaces 378 and 380 provide at least 30 or 40 percent of
the total contact area. In a further embodiment, the top and bottom
surfaces 378, 380 each have a width W.sub.gm (shown in FIG. 2) at
least 40 percent as wide as the width W of the support member 341,
and a depth D.sub.gm (shown in FIG. 2) at least 50 percent as deep
as the depth D of the support member 341.
In a preferred embodiment, the bone growth member 321 has a
non-threaded exterior. In this embodiment, the bone growth member
321 can be inserted into the cavity 327 by sliding the growth
member 321 therein without requiring rotation. Additionally, the
non-threaded configuration of the growth member 321 eliminates the
need for tapping threads into the bone support member 341 or the
opposing vertebral end plates between which the growth member 321
is desired to be implanted.
Referring to FIG. 3, the bone implant 320 has a dome shape for
limiting end plate removal and thereby minimizing subsidence. By
"dome shape", it is meant that the implant is curved or tapered on
the top and bottom surfaces 378 and 380 such that a thickness of
the implant increases in a direction extending from the outer
perimeter of the support member 341 toward the mid-line ML. In one
embodiment, the degree of curvature of the dome is defined by a
3-inch radius.
Other implant configurations are disclosed in U.S. application Ser.
Nos. 60/325,585 and 60/325,804 which are hereby incorporated by
reference.
C. End Cap
FIGS. 7A 7D illustrate an optional cap 350 for positioning in
cavity 327 between arms 325 and 326. In the illustrated embodiment,
cap 350 has a first bearing surface 351, a second bearing surface
352, an inner surface 353 and an outer surface 354. Bearing surface
351 includes an engaging surface 352 which can be similar to that
of implant 320 (bearing surface 352 can also include an engaging
surface). On each side, cap 350 includes a tab 360 and 361. Tabs
360 and 361 are configured to pass into grooves 337 and 336. As
illustrated in FIGS. 7A and 7B, tab 360 (and 361) have a major
height G.sub.M, and minor height G.sub.m. The difference in height
G.sub.M and G.sub.m provides tabs 360 and 361 with a diverging
taper from inner surface 353 to outer surface 354. Thus, when tabs
360 and 361 have passed into grooves 337 and 336 as cap 350 is
advanced within arms 325, 326 the taper from height G.sub.m to
height G.sub.m is selected to provide for a snug fit between tabs
360 and 361 and grooves 336 and 337 to retain cap 350 in position.
That is, cap 350 is friction fit into implant 320. The grooves 336
and 337 of implant 320, and a cap, such as cap 350 can be used with
other implants, such as implants 120 and 140.
Cap 350 can also include a bore 365 that may be threaded (not
shown) which permits for attachment of an insertion tool having a
threaded male end to mate with bore 365.
II. General Implantation Method
To implant the implant 320, a discectomy is performed on a patient
to partially or completely remove a diseased disc between adjacent
vertebrae 20, 22 (see FIGS. 8A and 8B). With the disc material
removed, end plates 20', 22' of the adjacent vertebra 20, 22 are
distracted/separated (e.g., with a wedge distractor). After the
vertebra 20, 22 have been spaced-apart, first regions 24 (see FIGS.
9A and 9B) of the end plates 20', 22' are prepared/conditioned to
receive the bone implant 10. For example, the end plates 20', 22'
can be conditioned by rasping the end plates 20', 22' to remove
cartilaginous material from the end plates 20', 22' and to smooth
the cortical bone of the end plates 20', 22' by reducing surface
irregularities. Next, second regions 26 of the end plates 20', 22'
are prepared within the first regions 24 (see FIGS. 10A and 10B).
In a preferred embodiment, the second regions 26 have smaller areas
than the first regions 24 and are subsets or sub regions of the
first regions 24. In one embodiment, the second regions 26 are
prepared by using a cutting tool (e.g., a chisel) to remove the
cortical bone from the second regions 26 and expose underlying
cancellous bone. In this embodiment, the exposed cancellous bone at
the second regions 26 is preferably surrounded by partial rings 27
of cortical bone (e.g., including the epiphyseal ring).
After preparation of the end plates 20', 22', the bone support
member 341 is inserted between the distracted vertebrae 20, 22 (see
FIG. 11). As so inserted, the top and bottom load bearing surfaces
328, 329 of the support member 341 directly engage the partial
rings 27 of cortical bone to provide column support. After
implantation of the support member 341, the bone growth member 321
is inserted into the cavity 327 through the open end 342. As so
inserted, the top and bottom sides 378 and 380 of the growth member
341 directly contact the exposed cancellous bone of the second
regions 26 to provide a fusion lattice (see FIG. 12).
In a preferred embodiment, each first region 24 is co-extensive
with a majority of the surface area of each end plate 20', 22'. As
shown in FIGS. 9A and 9B, each first region 24 covers substantially
all of the surface area of each corresponding end plate 20', 22'.
Thus, in such an embodiment, the implant 320 is sized to fill a
majority of the intervertebral space between the end plates 20',
22' and to contact a majority of the surface area of each end plate
20', 22'. In one embodiment, each second region 26 defines an area
that coincides with 20 80 percent of the total area defined by each
corresponding first region 24. In another embodiment, each second
region 26 defines an area that coincides with 30 70 percent of the
total area defined by each corresponding first region 24. In yet
another embodiment, each second region 26 defines an area that
coincide, with 40 60 percent of the total area defined by each
corresponding first region 24.
III. Implantation Kit
FIG. 13 illustrates an embodiment of a kit (i.e., an instrument
set) for implanting the bone implant 320 of FIG. 1. The kit
includes a wedge distractor 50 for providing a desired spacing
between two vertebrae desired to be stabilized. The kit also
includes a portal 52 for maintaining the spacing between the
vertebrae after the wedge distractor 50 has been removed from
between the vertebrae. The portal 52 includes a window 54 for
allowing access to the space between the distracted vertebrae.
Certain embodiments of the wedge distractor and portal system have
previously been disclosed in U.S. Pat. No. 6,224,599, incorporated
herein by reference. The kit further includes instruments that can
be inserted through the window 54 of the portal 52 for preparing
the vertebral end plates. For example, the kit includes a rasp 600
for removing cartilage from the vertebral end plates and for
conditioning the cortical bone of the vertebral end plates. A box
chisel 510 is included in the kit for removing cortical bone from
the vertebral end plates to provide regions of exposed cancellous
bone.
The box chisel 510 includes a hollow handle 518 configured to slide
over a shaft 603 of the rasp 600 such that the shaft 603 functions
as a guide for controlling the cutting location of the chisel 510.
A side handle 701 having an alignment pin 703 is adapted to
maintain rotational alignment between the rasp 600 and the box
chisel 510. The alignment pin 703 inserts within an opening 605
defined by the shaft 603 of the rasp 600 and also extends through a
slot 550 defined by the handle 518 of the chisel 510. The slot 550
allows the chisel 510 to be moved axially back and forth along the
rasp handle to provide a chiseling motion. As the chisel 510 is
moved along the rasp handle, the pin 703 slides along the slot 550.
The range of axial motion of the chisel 510 is limited by the
length of the slot 550. During chiseling, the side handle 701 is
preferably grasped to stabilize the rasp 600. A slap hammer 501 can
be used to provide greater impact forces for cutting the vertebrae
with the chisel 510. The slap hammer 501 includes a slot 503 for
allowing the slap hammer 501 to be moved past the alignment pin 703
when slid over the handle 518 of the chisel 510.
The kit further includes an insertion tool 800 having an insertion
head 803 (also referred to as a "working end") sized to fit within
the cavity 327 of the bone support member 341. In use, the bone
support member 341 is mounted on the insertion head 803, and the
insertion tool 800 is used to insert the bone support member 341
between the distracted and pre-conditioned vertebrae. Thereafter,
the insertion head 803 is removed from the cavity 327 of the bone
support member 341, and the growth member 321 is inserted into the
cavity 327 through the open end 342 of the cavity 327.
Alternatively, a conventional tool, such as a forceps, can be used
to insert the growth member 321 into the cavity 327. After the
implant 320 has been implanted into the intervertebral space, a
portal extractor 60 can be used to remove the portal 52.
A. Wedge Distractor, Portal and Portal Extractor
FIG. 14 shows the wedge distractor 50 and the portal 52 of the kit
of FIG. 13 in alignment with one another. The wedge distractor 50
includes a generally rectangular base portion 64. A back side 65 of
the base portion 64 defines a threaded opening (not shown) sized to
receive a threaded end of a handle 66. A vertebral wedge 68
projects forwardly from a front side 67 of the base portion 64.
The portal 52 includes a generally rectangular frame 70 defining
the portal window 54. The portal window 54 is sized to receive the
wedge distractor 50 with a friction fit between the base portion 64
of the wedge distractor 50 and the frame 70 of the portal 52. The
portal 52 also includes spaced apart distraction paddles 74 that
align on opposite sides of the vertebral wedge 68 when the wedge
distractor 50 is press fit within the portal 52. The distraction
paddles 74 and the vertebral wedge 68 preferably have substantially
the same side profile.
Referring to FIG. 13, the portal extractor 60 is sized to fit
within window 54 of portal 52. Handle 66 (shown in FIG. 14)
preferably connects to extractor 60. Tab 63 of extractor 60 fits
within opening 65 of portal 52 to allow portal 52 to be pulled from
the intervertebral space.
B. Rasp
FIG. 15 is a top view and FIG. 16 a side view of the rasp 600 of
the kit of FIG. 13. The rasp 600 is adapted to function as both as
a trial sizer, i.e. for a particularly sized and shaped implant,
and a rasp. Rasp 600 has a proximal end 601 and a distal end 602
spaced along longitudinal axis X--X. At the proximal end 601 of
shaft 603, there is a roughened area 604 that can be in the form of
knurls, etchings, grooves, ridges, or other suitable patterns to
enhance manual gripping of the shaft 603. The opening 605 for
receiving the alignment pin 703 of handle 701 extends transversely
through the proximal end 601 of the shaft 603. As previously
indicated, the opening 605 and alignment pin 703 assist in
maintaining rotational alignment between the rasp 600 and the
chisel 510.
At the distal end 602, rasp 600 includes a rasp head 606. In the
illustrated embodiment, rasp head 606 includes an outer wall 607,
an inner wall 608 and has a generally "C-shaped" configuration with
a first arm 609 continuous with a second arm 610. The inner wall
608 defines a pocket or receptacle which is sized to complement and
receive the distal end of the chisel 510. The first arm 609 and
second arm 610 are spaced apart from the shaft 603. Rasp head 606
includes a first engaging surface 611 and a second engaging surface
612. In the illustrated embodiment, the first and second engaging
surfaces 611, 612 have ridges 613 (see FIGS. 17 19). In alternative
embodiments, knurls, etchings, teeth, grooves or other suitable
patterns may be substituted for ridges 613.
As illustrated best in FIG. 17, in this embodiment, rasp head 606
has a major height H.sub.M and minor height H.sub.m. The taper from
the major height to the minor height can be from about 0.degree. to
about 16.degree.. The shape and configuration of the rasp head 606
corresponds to the shape and configuration of an implant. In one
embodiment, the rasp head 606 corresponds in size and configuration
with the support component 341 of the two-part implant 320 of FIGS.
1 4. In such an embodiment, the rasp head 606 preferably has the
same lordotic taper angle and the same dome curvature as the
support member desired to be implanted. The space between the first
and second arms 609, 610 of the rasp head 606 corresponds generally
with the shape of the growth component 321 of the implant 320. It
will be appreciated, however, that the configuration of the rasp
head 606 can be square, rectangular, circular, oval, etc.,
depending on the configuration of the implant(s) to be inserted
into the channel.
As a trial sizer, the rasp 600 provides a means for determining the
appropriate size bone cutting instrument and implant to use for a
particular implant site. Multiple rasps 600 are provided, with
incrementally different sized, shaped, and/or tapered rasp heads
606 corresponding to different sized, shaped, and/or tapered
implants. The surgeon inserts and removes the various rasps 600 and
determines (e.g., via evaluation of the frictional fit) which one
is the correct size for the intervertebral space. The ridges 613 on
the upper and lower surfaces of the rasp head act as a rasp to
condition the end plates of the upper and lower adjacent
vertebrae.
Proximal to the distal end 602, the shaft 603 of the rasp 600 also
includes markings 614 at predetermined distances from the distal
edge 615 of the rasp head. During use, markings 614 provide the
surgeon with an indication of the depth of distal penetration of
rasp 600 between adjacent vertebrae.
C. Box Chisel
FIG. 20 is a top view and FIG. 21 a side view of the chisel 510
shown in the kit of FIG. 13. Chisel 510 has a proximal end 515 and
a distal end 516 spaced along longitudinal axis X--X. At the
proximal end 515 of shaft 517 there is a handle 518 for operating
chisel 510. The handle 518 has a roughened area 519 that can be in
the form of knurls, etchings, grooves, ridges, or other suitable
patterns to enhance manual gripping of the handle 518. At the
distal end 516, chisel 510 includes a first cutting edge 520, a
second cutting edge 521, and third and fourth cutting edges 522 and
523. In the illustrated embodiment, cutting edges 520, 521, 522 and
523 are at the distal end of chamber 525. First, second, third, and
fourth cutting edges 520, 521, 522 and 523 are beveled 520a, 521a,
522a, and 523a, respectively, to facilitate cutting and removal of
bone. An internal hollow bore 527 extends from the proximal end 515
through the chisel 510 to the distal end 516 to receive the shaft
603 of rasp 600 and to receive bone.
In the illustrated embodiment, elongated openings 550 and 551
extend through the handle 518 and shaft 517, respectively, of the
chisel 510. As described previously, opening 550 allows for
alignment of the chisel 510 with rasp 600. Opening 551 provides
additional access to the internal bore 527 for cleaning the
instrument and reduces the weight of the instrument.
FIG. 22 is a distal end-on view of chisel 510 showing that first
and second cutting edges 520 and 521 define a height dimension
C.sub.H and the cutting edges 522 and 523 define a width dimension
W.sub.C. The perimeter configuration of cutting edges 520, 521,
522, and 523 in FIG. 22 is a rectangular shape particularly suited
for preparing a channel or implant bore between adjacent bones for
insertion of a two-part implant having a configuration such as that
of the implant 320 shown in FIG. 1.
As previously indicated, implant 320 includes growth member 321,
such as cancellous bone, and support member 341, such as cortical
bone. The growth member 321 has a similar size and shape as the
distal end of the chisel 510 (e.g., dimension W.sub.gm of growth
member 321 corresponds to dimension W.sub.C of chisel 510 and
dimension H.sub.gm of growth member 321 corresponds to dimension
C.sub.H of chisel 510). Also, the end curvature (i.e., at end 370)
of the growth member 321 corresponds to the curvature of edges 520
and 521 of the chisel 510. The support member 341 has a similar
size and configuration as the rasp head (see for example FIGS. 15,
16). The support member 341 of the implant may be the same size as
the rasp head, or it can be larger or smaller than the rasp head.
The support member 341 of the implant can be about 0 mm to about 4
mm larger in height than the rasp head. The height dimension
C.sub.H of the chisel 510 can be about 3 mm taller than the maximum
height of the support member 321 of the implant. It will be
appreciated, however, that the perimeter configuration of cutting
edges 520, 521, 522, and 523 can be square, circular, oval, etc.,
depending on the external configuration of the implant to be
inserted into the channel. The length of the first and second
cutting edges 520 and 521 can vary to correspond with the depth of
the vertebrae.
To cut different sized channels, a set of chisels 510 will be
available which has instruments with incrementally different sizes
of cutting edges 520, 521, 522, 523 corresponding to a particular
size implant. For example, chisels 510 having first and second
cutting edges 520, 521 with different heights C.sub.H will be
available to permit the surgeon to select a cutting edge height
corresponding to a particular disc space height. In addition, it
will be appreciated that the illustrated cutting edges 520 and 521
(and 522 and 523) are parallel. In alternative embodiments, cutting
edges 520 and 521 (and 522 and 523) can form a converging or
diverging taper.
D. Insertion Tool
FIGS. 23 25 illustrate the insertion tool 800 of the kit of FIG.
13. As illustrated, implant insertion tool 800 has a proximal end
801 and a distal end 802 having a working end 803. Working end 803
includes tabs 804 and 805 that fit cooperatively within grooves
336, 337 of the support member 341 of the implant 320. In addition,
the working end 803 includes a slot 806 that permits
resilient/elastic arms 807 and 808 to flex or expand laterally away
from axis A.sub.T.
In a typical embodiment, arms 807 and 808 are spring biased to
expand away (e.g., laterally) from axis A.sub.T in the normal,
relaxed position. A sleeve 820 (FIGS. 26 28) can then be slid from
the proximal end 801 of the insertion tool 800, over the slot 806,
to force arms 807 and 808 towards (e.g. medially) axis A.sub.T.
That is, when the sleeve is advanced distally it brings arms 807
and 808 together towards axis A.sub.T. In this position, the
working end 803 of implant insertion tool 800 can be inserted into
an implant. Similarly, where useful for additional control, tabs
804 and 805 can be inserted into grooves 336, 337 of an implant.
The sleeve can then be slid towards the proximal end to allow arms
807 and 808 to expand away from axis A.sub.T to provide friction
holding of an implant on the working end 803. After placement of an
implant, the sleeve can be slid distally to bring arms 807 and 808
back toward axis A.sub.T to remove implant insertion tool 800,
leaving the implant in place. Other arrangements providing for
expansion and contraction of arms 807, 808, relative to axis
A.sub.T also are contemplated by this disclosure
Thus, an implant can be mounted on the working end 803 of implant
insertion tool 800 allowing the surgeon to manipulate an implant
via tool 800 into a suitable position at the fusion site.
Referring back to FIGS. 23 and 24, in one embodiment the insertion
tool 800 has a threaded region 809 at the proximal end 801. The
threaded region 809 threads within a distal end 851 of a handle 850
(shown in FIGS. 29 31). The handle 850 has a roughened area 852
that can be in the form of knurls, etchings, grooves, ridges, or
other suitable patterns to enhance manual gripping of the handle
850. In one embodiment, the distal end 851 of the handle 850 has
exterior threading to match internal threading 821 on a sleeve 820.
The sleeve 820 is hollow and has a bore 822 extending from the
proximal end 823 to the distal end 824, and which is sized to fit
over the proximal end 801 of the implant insertion tool 800. When
the sleeve 820 is not being used to force the arms 807, 808 of the
insertion tool toward one another, the internal threadings 821 can
be threaded on the distal end 851 of the handle 850 to prevent
unintended sliding of the sleeve 820.
FIGS. 32 and 33 illustrate an alternative embodiment of an implant
insertion tool 400 suitable for use with an implant of the
invention. As illustrated, implant insertion tool 400 has a
proximal end 401 including a handle 402 for operating the
instrument and a distal end 403 having a working end 404. Working
end 404 include tabs 405 and 406 that fit cooperatively within
grooves 336 and 337 of implant 320. Thus, implant 320 can be
mounted at the working end 404 of implant insertion tool 400
allowing the surgeon to manipulate implant 320 via tool 400 into a
suitable position at the fusion site.
IV. Method of Implantation Using Kit
In one embodiment, a technique for practicing the method of FIGS. 8
12 involves using the kit of FIG. 13. In practicing the method, a
window, approximately the width of the portal 52 is cut,
symmetrically about the midline, in the annulus and a complete
discectomy is performed. Preferably, the lateral annulus is
retained to act as a tension band around the implant 320.
After cutting the window in the annulus, the appropriate sized
wedge distractor 50 and portal 52 are selected based on
pre-operative templating. A sizing chart for various components of
the kit is set forth below. The dimensions listed correspond to the
heights of portions of the components that are inserted into the
intervertebral space.
TABLE-US-00001 INSTRUMENT LETTER CODE A B C D E PORTAL 10 mm 12 mm
14 mm 16 mm 18 mm DISTRACTOR WEDGE 10 mm 12 mm 14 mm 16 mm 18 mm
RASP/TRIAL 10 mm 12 mm 14 mm 16 mm 18 mm CORTICAL GRAFT 10 mm 12 mm
14 mm 16 mm 18 mm BOX CHISEL 13 mm 15 mm 17 mm 19 mm 21 mm INSERTER
HEAD 13 mm 15 mm 17 mm 19 mm 21 mm CANCELLOUS BLOCK 13 mm 15 mm 17
mm 19 mm 21 mm
Once the wedge distractor 50 and portal 52 of the appropriate size
have been selected, the portal 52 is inserted over the wedge
distractor 50, and the combined unit is then delivered into the
midline of the disc space until a desired spacing and annular
tension is achieved between the adjacent vertebrae 20, 22. Proper
placement is achieved when the portal 52 is flush with the
vertebrae 20, 22 as shown in FIG. 34. The proper position of the
portal 52 can be confirmed by utilizing fluoroscopy.
With the portal in the position shown in FIG. 34, the slap hammer
501 can be used to help facilitate the removal of the wedge
distractor 50 from the portal 52. Additional discectomy or
posterior decompression can be completed, if necessary.
After the wedge distractor 50 has been removed, a rasp 600 of the
appropriate size is selected. The end plates 20', 22' are then
prepared by inserting the head of the rasp through the portal 52
and rasping in an anterior/posterior direction. Preferably, the
rasp 600 is advanced until shoulder 607 of the rasp is adjacent the
posterior most edge 51 of the portal 52 (see FIG. 35). In this
position, the thickness of the rasp head is slightly larger (e.g.,
about one-half millimeter) than the portal paddles. In this manner,
the rasp prepares the first regions 24 of the end plates 20', 22'
as shown in FIG. 9A. Fluoroscopy can be used to ensure proper
placement of the rasp within the disc space.
Once the end plates 20', 22' have been prepared with the rasp as
indicated above, a box chisel 510 of the appropriate size is
preferably selected. Box chisel 510 is then inserted over the shaft
603 of the rasp 600. Rotational alignment between the rasp 600 and
the chisel 510 is provided by the pin 703 of side handle 701 (see
FIG. 13).
When rotational alignment between the rasp 600 and the box chisel
510 achieved, the chisel 510 is slid along the shaft 603 of the
rasp toward the vertebrae 20, 22. The chisel 510 is then impacted
(e.g., with slap hammer 501) against the vertebrae 20, 22 until
edges 522 and 523 of the chisel 510 contact the back side 617
(shown in FIG. 15) of the rasp head (see FIG. 36). Thereafter, the
rasp 600 and chisel 510 combination can be removed from the
intervertebral space using the slap hammer 501.
After the rasp 600 and box chisel 510 have been removed, an
insertion head 803 having a size corresponding to the size of the
rasp 600 and chisel 510 is selected. The insertion sleeve 820 is
placed over the shaft of the insertion tool 800 and slid toward the
insertion head 803 causing the arms 807, 808 of the insertion head
803 to be flexed together. Thereafter, the support member 341 of
the implant 320 is inserted onto the insertion head 803 such that
tabs 804, 805 of the insertion head fit within the corresponding
grooves 336, 337 of the support member 341 (see FIG. 37). The
sleeve 820 is then slid away from the insertion head 803 and
threaded on the handle 850 of the insertion tool 800. With the
sleeve 820 pulled back, the arms 807, 808 of the insertion head
flex outwardly to securely hold the support member 341 on the
insertion head.
The insertion tool 800 is then used to insert the support member
341 through the portal 52 into the intervertebral space between the
vertebrae 20, 22. Light impaction may be utilized to deliver the
support member 341 into its final position. Final positioning is
achieved when the insertion head contacts a positive stop 27 formed
in the vertebrae 20, 22 by the chisel 510 (see FIG. 38).
Thereafter, the inserter sleeve 820 is unthreaded from the inserter
handle 850 and pushed toward the inserter head 803 to release the
inserter head 803 from the support member 341. The insertion tool
800 is then removed from the support member 341 leaving the support
member 341 within the intervertebral space.
After the support member 341 has been implanted, a growth member
321 having a size that corresponds to the support member 341 is
selected. Preferably, the growth member 321 has a height that is at
least two millimeters, and preferably about three millimeters
larger than the corresponding support member 341. A tool such as a
forceps 29 is used to place the growth member 321 into the channel
(i.e., region 26 shown in FIGS. 10B 12) created by the chisel 510
(see FIG. 39). A tamp can be used to tap the growth member into the
channel. Once the growth member 321 is in its final position, the
portal extractor 60 is used to remove the portal 52 as shown in
FIG. 40. The procedure is then finalized by conducting conventional
surgical closure and post-operative care procedures.
V. Alternative Implant Configuration
FIGS. 41 44 illustrate an alternative embodiment of an implant 140.
According to this embodiment, implant 140 includes a body 141
having a "C-shaped" configuration comprising a first arm 142
continuous with a second arm 143 forming a space 144 therebetween.
Body 141 also includes an external wall 146 and an internal wall
147. As best illustrated in FIGS. 8a and 8c, the facing surfaces of
arms 142 and 143 are concave 142a, 143a, respectively. First
bearing surface 150 and second bearing surface 151 are planar.
However, in an alternative embodiment, one or both of bearing
surfaces 150 and 151 could be configured as described for implants
70, 80 or 100.
A central void 155 is bounded by inner wall 147 and is continuous
with opening 144 between arms 142 and 143. Thus, body 141 is a
support component which can receive a growth component 153 in
central void 155. In the illustrated embodiment, growth component
153 can be a dowel of cancellous bone.
The implants described herein can be included in a kit comprising a
plurality of incrementally sized implants which can be selected for
use by the clinician based on the size needed for a particular
patient. In other embodiments, kits will be provided which include
instrumentation for performing an implant procedure with or without
a plurality of incrementally sized implants. Further, surface
preparation tools (e.g., rasps and cutting tools) other than those
specifically depicted herein can be used to practice various
aspects of the invention.
Having now described the present invention, it will be apparent to
one of ordinary skill in the art that many changes and
modifications can be made in the invention without departing from
the spirit or scope of the appended claims.
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